2121212221 has 8 divisors (see below), whose sum is σ = 2199607200. Its totient is φ = 2043167280.

The previous prime is 2121212209. The next prime is 2121212263. The reversal of 2121212221 is 1222121212.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 2121212221 - 2⁵ = 2121212189 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 2121212195 and 2121212204.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2121212021) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 75135 + ... + 99436.

It is an arithmetic number, because the mean of its divisors is an integer number (274950900).

Almost surely, 2^2121212221 is an apocalyptic number.

It is an amenable number.

2121212221 is a deficient number, since it is larger than the sum of its proper divisors (78394979).

2121212221 is a wasteful number, since it uses less digits than its factorization.

2121212221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 175019.

The product of its digits is 64, while the sum is 16.

The square root of 2121212221 is about 46056.6197305013. The cubic root of 2121212221 is about 1284.8764628622.

Adding to 2121212221 its reverse (1222121212), we get a palindrome (3343333433).

It can be divided in two parts, 21212 and 12221, that added together give a palindrome (33433).

The spelling of 2121212221 in words is "two billion, one hundred twenty-one million, two hundred twelve thousand, two hundred twenty-one".